Fsharp: Type

What is reference type in F sharp?

(ai answer)

A reference type is a type whose values are stored on the heap and accessed through a pointer. In F#, the main ones are classes, records, unions, arrays, lists, and strings.

Can you define the reference type in a more formal way without referring to heap? Because that relates to the hardware.

A reference type is a type whose values are accessed indirectly through a reference — a value that identifies another value rather than being the value itself. The reference is a first-class value: it can be stored in variables, passed to functions, and compared for identity. Two references can point to the same underlying value, so mutation through one is visible through the other.

what's strut in F Sharp

(ai answer)

Struct (likely what you meant) in F# is a value type for small, frequently copied data. Use the struct keyword or [<Struct>] attribute.

type Point =
    struct
        val X: float
        val Y: float
        new(x, y) = { X = x; Y = y }
    end

Stored on the stack (or inline), passed by value. More efficient than classes for simple aggregates.

how to explain struct in a formal way without referring to stack because that relates to implementation

(ai answer)

A struct in F# is a value type that groups a small collection of related fields (and optional members) into a single unit with value semantics.

Assignment, parameter passing, and returns copy the entire contents. Two struct values are equal when their fields are equal; they have no independent identity.

Use structs for compact, frequently copied data whose meaning is fully determined by their contents.